The prior art is replete with numerous examples of heating assemblies which are operable to impart energy to a liquid which is enclosed within a vessel. For example, so-called "block heaters" have been utilized for more than 50 years on internal combustion engines to maintain lubricating fluids in the motors at a given temperature to facilitate rapid ignition at cold starting temperatures. Other heating assemblies have been designed for similar or other purposes. Commonly, these assemblies include a heating element, a thermostat, and a base plate for securing the heating element in an appropriate orientation relative to the vessel that encloses the fluid. As should be understood, the thermostat has typically facilitated the energizing, and deenergizing of the heating element under appropriate operational conditions.
While these heating assemblies have operated with varying degrees of success, they have shortcomings which have detracted from their usefulness. More specifically, under some operational conditions, heat energy from the fluid enclosed within the vessel may move into the surrounding vessel, and base plate supporting the heating element such that the accompanying thermostat prematurely deenergizes the heating element. Further, in a "dry tank" condition, that is, where the heating element is not immersed in the fluid; the base plate, and the vessel then become a heat sink, that is, absorbing the excess heat energy produced by the heating element. This absorption of heat energy, if left unchecked, may cause the heating element to degrade or become permanently damaged before the accompanying thermostat can deenergize same. Yet further, if the base plate effectively acts as a heat sink, it will prevent the heating element from becoming energized, when the tank is subsequently filled with fluid, until such time as the heat energy in the base plate flows from the base plate into the surrounding fluid thus allowing the thermostat to reset.
Yet a further shortcoming with the prior art devices relates to characteristics inherent in their design. For example, designers of these previous assemblies have attempted to address the problems noted above by providing remote temperature sensing, and various mechanical arrangements which have increased the complexity of the heating element and its associated costs of manufacturing. These associated design changes have not measurably increased the reliability of same, and under some environmental conditions, may cause the assembly to fail.
An improved heating assembly is the subject matter of the present application.